sysdep.h

它通过提供glibc兼容使得应用程序移植到较小的c 库时相当得容易. 它能够应用到带虚拟存储的Linux和uClinux上.在大多数带MMU部件的平台上为使它更加紧凑,它也能够编译成共享库.uClib

/* Assembler macros for CRIS.
   Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#ifndef _SYSDEP_H_
#define _SYSDEP_H_

#ifndef C_LABEL

/* Define a macro we can use to construct the asm name for a C symbol.  */
#ifdef  __STDC__
#define C_LABEL(name)           name##:
#else
#define C_LABEL(name)           name/**/:
#endif

#endif /* C_LABEL */

#define __STR(x) #x
#define STR(x) __STR(x)

/* Mark the end of function named SYM.  This is used on some platforms
   to generate correct debugging information.  */
#ifndef END
#define END(sym)
#endif

#define C_SYMBOL_NAME(name) name

#ifdef	__ASSEMBLER__

/* Syntactic details of assembly-code.  */

/* It is *not* generally true that "ELF uses byte-counts for .align, most
   others use log2 of count of bytes", like some neighboring configs say.
   See "align" in gas/read.c which is not overridden by
   gas/config/obj-elf.c.  It takes a log2 argument.  *Some* targets
   override it to take a byte argument.  People should read source instead
   of relying on hearsay.  */
#define ALIGNARG(log2) log2

#define ASM_GLOBAL_DIRECTIVE .globl 
#define ASM_TYPE_DIRECTIVE(name,typearg) .type name,typearg
#define ASM_SIZE_DIRECTIVE(name) .size name,.-name

/* The non-PIC jump is preferred, since it does not stall, and does not
   invoke generation of a PLT.  These macros assume that $r0 is set up as
   GOT register.  */
#ifdef __PIC__
#define PLTJUMP(_x) \
  add.d	C_SYMBOL_NAME (_x):PLT,$pc

#define PLTCALL(_x) \
  jsr [$r0+C_SYMBOL_NAME (_x):GOTPLT16]

#define SETUP_PIC \
  push	$r0						@ \
  move.d $pc,$r0					@ \
  sub.d	.:GOTOFF,$r0

#define TEARDOWN_PIC pop $r0
#else
#define PLTJUMP(_x) jump C_SYMBOL_NAME (_x)
#define PLTCALL(_x) jsr  C_SYMBOL_NAME (_x)
#define SETUP_PIC
#define TEARDOWN_PIC
#endif

/* Define an entry point visible from C.  */
#define	ENTRY(name) \
  .text							@ \
  ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME (name) 		@ \
  ASM_TYPE_DIRECTIVE (C_SYMBOL_NAME (name), function)	@ \
  .align ALIGNARG (2) 					@ \
  C_LABEL(name)						@ \
  CALL_MCOUNT

#undef	END
#define END(name) \
  ASM_SIZE_DIRECTIVE (C_SYMBOL_NAME (name))

#define PSEUDO(name, syscall_name, args) \
  ENTRY (name)                      @ \
  DOARGS_##args                     @ \
  movu.w SYS_ify (syscall_name),$r9         @ \
  break 13                      @ \
  cmps.w -4096,$r10                 @ \
  bhs   0f                      @ \
  nop                           @ \
  UNDOARGS_return_##args

#define PSEUDO_END(name) \
0:                          @ \
  SETUP_PIC                     @ \
  PLTJUMP (__syscall_error)               @ \
  END (name)

/* If compiled for profiling, call `_mcount' at the start of each function.
   FIXME: Note that profiling is not actually implemented.  This is just
   example code which might not even compile, though it is believed to be
   correct.  */
#ifdef	PROF
#define CALL_MCOUNT \
  push	$srp						@ \
  push	$r9						@ \
  push	$r10						@ \
  push	$r11						@ \
  push	$r12						@ \
  push	$r13						@ \
  SETUP_PIC						@ \
  PLTCALL (_mcount)					@ \
  TEARDOWN_PIC						@ \
  pop	$r13						@ \
  pop	$r12						@ \
  pop	$r11						@ \
  pop	$r10						@ \
  pop	$r9						@ \
  pop	$srp
#else
#define CALL_MCOUNT		/* Do nothing.  */
#endif


#endif /* __ASSEMBLER__ */
#endif /* _SYSDEP_H_ */